of the Amazons Valley. 103 



able to the recent genus Fossar^ near Lacuna^ and to the 

 family Littorinidte. 



4. Hemisinus sulcatus, Conrad, op. ctt. pi. 10. fig. 2. 

 " An elegant species, closely allied to H. teneUus ; but it 

 has a longer last whorl and a narrower aperture." Mr. Conrad 

 considers this shell " a decidedly freshwater genus, a genus 

 living in South- American rivers." 



5. Dyris gracilis^ Conrad, op. cit. pi. 10. fig. 8. 

 Another extremely minute shell (about 3 lines in length) . Mr. 

 Conrad thinks the mouth similar to that of the genus Melania. 



6. Nerttina Ortoiit, Conrad, op. cit. pi. 10. fig. 5. 

 Nerttmapupa, Gabb,Amer.Journ. Conch, vol. iv. p. 197, pi. 16. 



PL V. figs. 2 a, h. 



I am inclined to regard these two species as probably 

 synonymous. Having received more than 250 specimens, I 

 think it possible to trace up all the variations between the 

 young and aged specimens, so as to connect them together. 

 The colour-markings are inconstant, and cannot be dealt with, 

 save as indicating varieties ; and the form of the shell varies 

 with the age. 



The Neritince occur both in fresh and brackish waters, two 

 West-Indian species even inhabiting the sea. 



7. Bulimus Imteiis, Conrad, op. cit. pi. 10. fig. 9. 



An outline is given of this, the only land-shell in the col- 

 lection. The author refers it to some subgenus of Bultmus, 

 probably Plectostylus, Beck. 



Odostomia ? PI. V. figs. 4 a, h. 



I venture to think the little shell figured in our plate (fig. 4) 

 is referable to this genus. Odostomia is sometimes found in 

 brackish water. Fig. a is of the natural size ; fig. h the same 

 enlarged. I prefer, however, to await better specimens before 

 describing it further. 



CONCHIFERA. 

 Anodon, Cuvier. 



Shell like Unto, but edentulous ; oval, smooth, rather thin, 

 compressed when young, becoming ventricose with age. 



Anodon Batesii, sp. nov. PL V. fig. 10. 



I beg permission to dedicate this very beautiful and unique 

 Amazonian Anodon to my friend Henry Walter Bates, Secre- 



